During processing, such as between successive processing stations, printed products are usually transported in streams. In such conveying streams, the printed products e.g. lie one after the other or overlapping each other (scaled stream) on a conveying surface and are conveyed in a direction substantially parallel to their main surfaces (the largest surfaces of the products) or else the printed products are individually held in a hanging position, e.g. by grippers, so that their main surfaces are substantially perpendicular to the conveying direction.
Printed products are collected in stacks for different kinds of processing (intermediate storage, packing) and are further conveyed and/or processed in the form of stacks (bundles, handleable stacks or packages).
Usually, a stacking device forms the end of a conveying stream, i.e. all printed products conveyed in a conveying stream are stacked by the device. The capacity of a device for further conveying or processing the stacks is to be adapted to the conveying capacity of the conveying stream or else switch points must be introduced into the conveying stream which guide the products to a plurality of parallel stacking devices. The number of printed products which a device for further conveying or further processing (e.g. for strapping or packaging) of stacks is able to handle per time unit is substantially constant and supplying the products causes no problems as long as all stacks to be produced contain a substantially equal number of printed products. If, however, stacks containing very different numbers of printed products are to be produced (e.g. standard packages and odd packages or packages of standard size consisting of printed products with different thicknesses) the capacity of the stack-processing devices regarding number of printed products being taken in by them is subject to very fast changes. Thus, difficulties arise which are additionally increased if the stack-forming must be adapted to the characteristics of the individual printed products (individualized printed products).
In publication CH-667854 (or U.S. Pat. No. 4,683,708) a plant is described for selectively dropping printed products supplied in a scaled stream into a stacking shaft or for conveying them further to a further stacking device. In the further stacking device, the stacks are formed and immediately packed into film and are then conveyed away. The plant can only be used if the major part of printed products is dropped into the stacking shaft or if the conveying performance of the supply stream is adapted to the momentary capacity of both stacking devices but especially of the further stacking device. Using the described plant it is not possible to remove individual printed products from the scaled stream for dropping them into the stacking shaft, i.e. it is not possible to handle individualized printed products individually. For these reasons the described plant is restricted to a very narrow range of application.